This invention relates generally to injection molding and more particularly to apparatus for side gating from a heated nozzle to a number of cavities spaced around the nozzle through side gate seals, each of which have a hot tip.
As seen in the applicant's U.S. Pat. No. 4,795,338 which issued Jan. 3, 1989, hot tip gating from a nozzle to a single gate on the longitudinal axis of the nozzle is well known. Edge gating from a nozzle through a number of edge gate seals is also well known, as seen in U.S. Pat. No. 4,981,431 to Schmidt which issued Jan. 1, 1991. While these previous seals have an outer sealing flange or rim, in order to prevent melt leakage it is necessary to provide sealing contact between the outer face of the rim and the mold. A space is provided around the circumference of the sealing rim to allow for longitudinal thermal expansion and contraction of the nozzle. While this is satisfactory for some applications, it has the disadvantage that it is difficult to provide the close tolerances necessary to ensure a tight seal between the outer face of the rim and the mold. Also, different operating temperatures for different applications results in different thermal expansion of the edge gate seals.